Earthquake Information:

5. What are the main types of seismic waves?

Seismic waves can be divided into two groups based on their passage through the Earth's body.

(1) Body waves: Waves that travel inside the Earth's interior. According to the wave property these waves can be divided into the following two classes:
(i) P-waves (primary wave, longitudinal or pressure wave): They are similar to sound waves. The particles vibrate along or parallel to the direction of wave propagation. These are the fastest waves.
(ii) S-waves (shear wave, secondary wave, or transverse wave): The particles vibrate perpendicular to the direction of the wave propagation. The vibration shakes horizontally and the velocity of the S-waves is next to that of the P-waves as they pass through the same medium.
(2) Surface waves: Waves that travel along the Earth's surface and the layers near the surface. These waves can generally be divided into the following two classes:
(i) Love waves: The particles vibrate on a horizontal plane and perpendicular to the direction of wave propagation.
(ii) Rayleigh waves: The particles vibrate on a vertical plane and follow a retrograde ellipse.

What are the main types of seismic waves?

When the seismic waves pass the medium, their particle motions are shown as in the diagram above.

 
4. What do the terms "hypocenter" and "epicenter" refer to?  6. What is "magnitude"?